The importance of accurate control of fertilizer mixtures has become increasingly apparent in recent years with the rapid progression of modern farming methods. By analysis of soil samples farm laboratories are now capable of providing precise requirements for fertilizer mixtures for individual farm fields. This fertilizer mixture information is commonly retained by fertilizer suppliers and is stored in computers. Typically when a customer orders fertilizer, the supplier will retrieve the customer's name and the fertilizer mixture information from the computer in the form of a paper print out. The print out will then be presented to a loading operator who is responsible for filling the order. The various fertilizer ingredients are dumped sequentially into a receptacle commonly referred to as a scale hopper, and are then weighed by a large scale having a dial indicator. The loading of the required amounts of each ingredient thus forms a batch which is carried to a mixer which operates to provide a uniformly mixed final product. After mixing, the batch is dumped into a field spreader unit. This process is repeated until the required amount of fertilizer has been processed. Review of this procedure reveals a very complex task for the operator responsible for the loading procedure. The factors he must consider include the weight capacity of the field spreader unit, the weight capacity of the scale hopper, the capacity of the mixer, the weight of each ingredient which is to be added to each batch, the total weight of each batch, and the total number of batches required. The procedure is further complicated by difficulty in accurately reading a dial indicator scale which is inherently unstable as it reacts to dumping from a bucket loader and which can be read only to plus or minus 30 pounds. As an example of a typical procedure, it is necessary for a loading operator to load, transport, dump, and weigh approximately 125 scoop loads from 5 or more fertilizer supply bins in order to prepare 5 batches which are required to make up 1 deliverable load of fertilizer. During a normal day an operator would repeat the scooping operation 1000 or more times.
It is readily apparent from the above that such an operation, without an automatic control system, is highly susceptible to error. In actual practice such errors have been in the form of excesses of a particular ingredient. In many instances these errors have damaged or ruined crops. Additionally, this system is totally dependent upon records kept by the operator as the loading progresses. These records which include the information necessary for billing, inventory control, and other record keeping requirements, are manually loaded into a computer at the end of each day.
The primary objects of the present invention are to obviate the above mentioned and other shortcomings of the systems described above.
These and other objects of the present invention will become apparent to those skilled in the art, as the description thereof proceeds.